• 500 ml (17 fl oz/2 cups) vegetable oil, for deep-frying
• Raita, to serve

Pani

• 100 g (3½ oz) tamarind pulp, soaked in 250 ml (9 fl oz/1 cup) water for 2 hours
• 250 g (9 oz) mint, leaves picked
• 1 teaspoon cumin seeds, dry-roasted and ground
• 2 teaspoons ground cumin
• 1 teaspoon rock salt
• ½ teaspoon freshly ground black pepper

Puri

• 2 tablespoons fine semolina
• 300 g (10½ oz/2 cups) atta flour (high-protein durum wheat flour)
• ½ teaspoon salt
• 45 ml (1½ fl oz) rice bran oil, plus extra for brushing

Potato Filling

• 4 boiling potatoes, such as russet or sebago, cooked and cooled
• ½ teaspoon salt
• 1 teaspoon chilli powder
• 2 tablespoons virgin coconut oil
• ½ teaspoon brown mustard seeds
• ½ small onion, diced
• 1 small dried red chilli, broken into pieces
• a sprinkling of Chaat masala, to taste

To make the pani, mash the soaked tamarind pulp with your hands and remove the seeds. Strain the pulp into a bowl and set aside. Using a blender or mortar and pestle, grind the mint leaves to a smooth paste with 250 ml (9 fl oz/1 cup) water. Add to the strained tamarind pulp, along with the remaining pani ingredients, and stir to combine. Set aside.

For the puri, put the semolina in a mixing bowl, add 100 ml (3½ fl oz) water and soak for 10 minutes. Add the atta flour, salt and rice bran oil and mix together, then turn out onto a work surface and knead into a firm dough. This is a slightly tricky dough: it needs to just come together, but not be too wet either. (You’ll know you’ve got it right when you cook them. If the puri float and puff, you have it! If they sink and don’t puff, add a little more water.) Rub some extra oil on the dough, cover with a wet tea towel and rest at room temperature for 30 minutes.

Roll the rested dough into 20 balls about the size of golf balls, then roll each one out into a small chapatti using a rolling pin.

To cook the puri, heat the vegetable oil in a deep heavy-based saucepan to 180°C (350°F), or until a cube of bread dropped into the oil turns brown in 15 seconds.

Without overcrowding the pan, cook three or four puri at a time, for about 3 minutes, until they turn brown, gently pushing them under the oil with a slotted spoon until they puff and turn crisp. Drain on paper towel and keep warm. For the potato filling, peel the potatoes and place in a bowl. Add the salt and chilli powder and mash, then set aside.

Heat the coconut oil in a frying pan over medium heat and fry the mustard seeds for a minute or two, until they start to pop. Add the onion and dried chilli pieces and cook for 3 minutes, or until the onion is golden. Tip the mixture over the mashed potato and mix together well. Sprinkle with chaat masala and check the seasoning. Keep warm.

For each serving, take two or three puri and gently push them into each other, into a stack of crispy goodness. (This is how you’d get them in a street food stall — but if you want to show them off, just place them on a plate, side by side.) Dollop with the potato filling and raita. Serve with a small bowl of pani.